Arkansas HVACR NewsMagazine November 2022

HVACR NewsMagazine November 2022

Tech News

Compression Refrigeration

Refrigerant Basics

A physician named John Gorrie built one of the first compression refrigeration machines, and it used air as the refrigerant. By compressing the air, it would increase in temperature, and heat could be rejected from it. He would then “rarify” or depressurize the air, dropping the temperature and allowing heat to be absorbed into the air from the water. The machine could then — eventually — produce ice.

A refrigerant is anything we use to move heat from one place to another using the compression refrigeration circuit. However, the history of refrigerants and the different kinds is quite diverse and interesting. H ave you ever noticed how your skin feels cool after you apply some rubbing alcohol to it? For a long time, scientists and inventors experimented with substances that evaporated easily at atmospheric pressure, like ether and alcohol. They noticed that these substances cooled the surface they left when they evaporated away. It was understood that substances remove heat as they boil (change from liquid to vapor) because that is one way our bodies reject heat while sweating. As the sweat evaporates, it removes heat from our skin, leaving us cooler. This is an “open” process; the alcohol, ether, or sweat leaves as it cools, so you always need more to keep the process going. The trick was to create a process that could be done repeatedly without lo sing the “refrigerant” to the atmosphere.

There were several issues with Dr. Gorrie's design. One big issue was that while he was using compression and expansion, he wasn't using the power of evaporation to increase the amount of heat that could be moved. It wasn't long before others began using refrigerants like ammonia, CO 2 , sulfur dioxide, and methyl chloride using the same compressing and expanding that Dr. Gorrie